Playdough-like particles could self-assemble into functional architectures, may change the face of 3D printing

Dec 5, 2017 | By Julia

A group of chemists at New York University (NYU) are reconfiguring the “building blocks” of life with a new particle that combines Playdough and Lego traits. All fun and games aside, these so-called patchy particles are 1/200th the width of a human hair, and can self-assemble into an endless array of unique architectures. According to their creators, there’s no limit on potential applications.

“Imagine that you want to build a castle, but instead of handpicking the bricks and patiently connecting them one by one, you simply shake the box of pieces so that they magically connect to one another in forming a full-featured castle," explains NYU assistant professor Stefano Sacanna. “These smart particles represent an important step forward for the realization of self-assembling new materials and micro-machinery."

Where do the Lego and Playdough traits come in? Via colloidal fusion, a new synthetic methodology developed by Sacanna and his associates. Much in the way that different pieces of playdough can be squeezed together to form new structures, colloidal fusion “squeezes” different chemical components together to create a new particle. Rather than a multicoloured playdough sculpture, however, the NYU-developed methodology creates a multi-functional building-block that contains complete instructions for self-assembly. A specialized software known as “Surface Evolver” allows the team to predict how exactly the preliminary cluster will evolve when “squeezed”, and what the resulting patchy particle will be.

This process of self-assembling micro-architectures is somewhat akin to the natural process of crystalization, in which atomic crystals self-assemble from a specific breakdown of sub-atomic particles. “In nature, extremely precise architectures, such as crystals, seamlessly grow from random soups of atoms," explains Sacanna. By using similar principles, he says, it’s possible to fabricate extremely precise micro-architectures without the need for human intervention.

According to Sacanna, the 3D printing industry could be completely revolutionized by the new innovation. That means not only 3D printing in miniature; colloidal self-assembly would also enable 3D printing fully functional architectures. “Say you want to print a model car,” says Sacanna. “Using colloidal self-assembly, you could print a car that is a fraction of a millimetre and that could someday actually run!"

Of course, miniaturization presents its own challenges for scientists. Directly manipulating particles 100 times smaller than a human cell is tricky to say the least. Hence Sacanna and his team explored a new methodology of self-assembly - what they call “nature’s manufacturing technology.” Still, this approach requires the advanced ability to develop building blocks that will behave according to a specific set of instructions. That means creating microscopic particles equipped with an “on-board instruction manual” for how to connect with neighbouring particles.

It’s a highly innovative technology that, for now, hasn’t left the confines of Sacanna’s lab, yet is already changing our perception of the world around us. “These particles will help us to understand—and allow to mimic—the self-assembling mechanisms that nature uses to generate complexity and functionalities from simple building blocks," Sacanna says.

Recently published in the scientific journal Nature, Sacanna’s research was co-authored by Gi-Ra Yi, a chemical engineering professor at South Korea’s Sungkyunkwan University, as well as NYU graduate students Zhe Gong and Theodore Hueckel.